As a F/OSS developer I am ideologically opposed to my work ever being used by the US' DoD or any of its organizations. Has anyone successfully built F/OSS products with a license that disallows use by military organizations, and if so - what is involved in maintaining that situation?
Also, the DoD in particular has sovereign immunity, so if they infringe your copyright, you somehow find out about it, and you sue them for it in the US, they can just refuse the lawsuit. The best you could do in that case is something like a WTO lawsuit, which, well, I don't think you can get by with less than a million dollars in legal fees. You could sue somebody like Boeing or Lockheed Martin but you're still going to have one hell of an uphill battle there. However, those organizations would probably prefer not to spend tens of thousands of dollars to fight your lawsuit, so they may comply with the license even if they would probably win in court.
The federal government has waived its sovereign immunity via statute for specific kinds of lawsuits, including for copyright infringement via 28 U.S.C. 1498(b).
There is also a school of thought that says that copyright infringement violates the Fifth Amendment's takings clause, but that has yet to be endorsed (or rejected) convincingly at a federal level.
> The best you could do in that case is something like a WTO lawsuit
There are WTO disputes, but these can only be brought by one WTO member (e.g., a sovereign government) against another and generally the outcome of WTO disputes does not involve compensation.
Quite an interesting conundrum, this - but I suppose one that is simply the state of things: if you want your stuff to be free and open, you cannot release it to the world and expect/demand that it will not be weaponized, as is the case with any and all technology. Sobering.
Simple: stop being a F/OSS developer, and only license your non-F/OSS software to the organizations you choose.
In my mind the alternative to the police and an army isn't peace but the rule of the strongest.
Ask any pacifist country that stood in Hitlers way.
(That said I never signed up for "peacekeeping" missions abroad how much I'd like to try to serve in the field: I'm principled too)
You can add a clause to the licence saying "the following people/organisations are specifically prohibited from using this code: US DoD, etc" - you may want to word this better to prevent loopholes, but that's the gist of it.